The best Science Fiction novel ever written is in my humble opinion: Dune, by the late Frank Herbert. Dune was published in 1965, but is still in print and can be purchased from for example Amazon.

Herbert wrote five sequels to the novel Dune: Dune Messiah (1969), Children of Dune (1976), God Emperor of Dune (1981), Heretics of Dune (1984), and Chapterhouse: Dune (1985). While the sequels are not as good as the first novel (how could they be, it is the world’s best SF novel after all…), they are still quite good and necessary reading for anyone who enjoys the Dune universe. Frank Herbert died on February 11, 1986.

Frank Herbert’s son Brian Herbert, has together with Kevin J. Anderson, written a number of novels in the Dune universe. Among those are the novels Hunters of Dune (2006) and Sandworms of Dune (2007), which continue the story from Chapterhouse: Dune. More information about all these novels can be found on http://en.wikipedia.org/wiki/Dune_universe.

Note: Make sure that you do NOT watch the terrible movie adaption from 1984, and you should probably stay away from the mini-series from 2000 too. Just read the book!